The proposed research deals with the neural mechanisms mediating the effects of circulating gonadol hormones on sexual arousal and copulatory performance of male and female rats. Two approaches are being used. In the first, we are using intracerebral hormone implants into the medial preoptic area (mPOA) of male rats, combined with knife cuts severing the medial forebrain bundle (MFB) of the hypothalamus, to test the hypothesis that the mPOA and MFB form part of a system through which circulating steroids influence the gating of sexual arousal into copulatory performance. The second approach is based on our work which suggests that brain DA-containing systems may play an important role in approach components of sexual behavior in both males and females, and that, at least for females, the "consummatory" component requires a functional blockade of DA in order for the female to switch from an active behavior pattern (i.e., soliciting) to the immobility posture (i.e., lordosis). We are following this work up at the pharmacological and electrophysiological levels and are employing several models of active and immobility behaviors.